Measuring mechanism



Jan. 5, 1937. F, M ASLOUGH l Y. 2,066,700-

" MEAsURmG MECHANISM Filed Aug. 2e, 1929 v 2 sheets-sheet 1:

z @la 57 2 Sheets-Sheet 2 M Jan. 5,

FU`N|TED-4STATES PATENT OFFICE y ma su. n, im. salame 88M seu... (am-51) My invention relates 'systems,' and relates particularly to pressure measuring systems adapted to remotely indicate a pressure exerted by a oonnnediluid.

An object of my invention is to provide an improved mechanism for remotely indicating the amount of liquid..contained in a receptacle.

object of my invention is to indicate. remotely thereof, the amount of liquidcontained in a receptacle.

Another object of remotely thereof, a lined fluid.

Another object of on the instrument topressuremeasuring my invention to indicate. pressure exerted by a' oonmy invention is to indicate, board of an automotive vehicle, the amount of liquid supply carried by `thel vehicle for the operation of vthe vengine thereof.

Another Aobject of my invention is to reliably indicate on the instrumentfboard of an automotive vehicle, thejamount of liquid fuel contained in a fuel tank disposed remotely thereto. Another object of `my invention is to accomplish each and every of the aforesaid objects by lelectrical means.

Another object of my invention is to provide an improved means of electrically indicating. at a distance, the potential `energy of a pressure, without the interposition of` fluid pressure communicating conduits extending between the indicating and pressure elements of the-system.

, Other objects of my invention andthe invention itself will become apparent by reference to 'the following description of certain 'embodi- 'ments of my invention, and which are 'illustrated in the accompanying drawings.

Referring to` the drawings: s f

Fig. 1 illustrates, largely diagrammatically, but comprising asectional view of an automotive vehicle gasoline tank, an embodiment of my invention.

Fig; `2 illustrates, in similar view, a bodiment of my invention.

`Fig. 3 illustrates a controlling mechanism, constructed in accordance with the embodiment of Fig. l, applied to a receptacle such as a gasoline second emtank of an automotivef vehicle, the view being in longitudinal medial section. l

Fig. 4 is a plan view of the apparatus of Fig. 3. Fig. 5 is a view of a heating element adapted to be employed in connection with any of the embodiments of my invention to support the heating winding.

Fig. 6 illustrates the element of Fig. described. l

Figs. 7 and ,B illustrate other embodiment apparatus pertaining to my invention.

.Referring now first to Figs. "1, 3, 4, 5 and 6, illustrating variously an Aembodiment: of my ina pai of metallic spools lfor 5, to carry out a purpose later A eign particles of dust,

bile desired, and

and including a gasoline gauge indicator 2. The

indicator 2, and .2 in the embodiment of Figs. 1 and 2, will be understood cto be preferably disposed forwardly in the driving compartment of the automobile, and the tank i and i', respectively, may be placed on any part of the automoin thefollowing description will be understood to be supported on thel chassis frame rearwardly of the passenger compartment. in the usual manner; also the'tank l may be of any suitable form, such as rectangular, illustrated. or of' ,other form, such as cylindrical.

In the embodiment of Figs. 1 and 3, to the bottom of the tank I, a anged cup element 3 is in any suitable way such as by screw threading the hollow stem of the cup into an internally threaded boss flange l, depending integrally from the tank i a fluid seal gasket being preferably interposed between the contiguous opposing vs urface'of the flange and the cup to prevent lossof the liquid fuel, which, otherwise might pass the screw threads.

Within the tubular stem 4, there is preferably rigidly carried. an upstandingtube 1, thereby projected, preferably vertically, within the tank i. near its top wall, the tube being 4preferably opened at its top andcomprising oneor more small apertures 8 through it'slateral-walls near its bottom end, 'preferably ush with the bottom inner wall of the tank, but-preferably substantially above an annular well t surrounding the tube 1l and provided for the reception of fordirt or the'like, which may in any waybe communicated to the interior of the tank I.

'I'he bottom end of the tube 1, below the apertures I, is provided with one or more means for restraining the rapid vcommunication of fluid between the spaces above and below such means.

In the embodiment illustrated, the fluid flow restraining means are in the i'orm of a pair of metallic discs I and I2, having minute orifices il and I4, adapted to communicate fluid preseures exerted on the one side of each disc, to the other side, but restraining the rate of charge of fluid pressures on its two sides.

Rigidly secured by its peripheral border by a metallic clamping ring I3, within the rim portion of the casing cup l, there is provided` a yieldable wall in the form of a diaphragm I adapted to material, and containing plurality of spaced clamping screws IB projected through openings in the border oi the diaphragm through the upper wall of the cup element 3 and into screw threaded apertures oi the ring' I3. Any means'oiinsuring that the joint between the casing 2 and the diaphragm l5, shall be proof against leakage of liquid fuel, may be employed, y

Such as by soldering, the use of gaskets, or the like. Y

In. the following description it will be understood that the contiguous suriacesfoi the dia.- phragm, clamping rings i3 and casing 3, are rvs ecui-ely soldered together by iirst tinning the surfaces, and then reheating them while in contact,

and after thescrews i8 have been tightly driven'.

An apparatus supporting annulus I9 is rigidly secured to the ring i3 by screws 2@ disposed at intervals around the ring and supports an appa-.

ratusV supporting frame 2|, a contact support 22, a circuit conductor insulating terminal 23, and a support 2 for a thermo-responsive warpablel strip 25. The apparatus supporting frame 2|, supporte` by a flange 26, an electromagnet 21, and

'by upturned ears 28, a pair oi pivot screws 29,

which in' turn pivotally support a swivelable armature 3G' for the electromagnet, which is integrally secured to a'- controlling tongue 3|, extendlng across the vcasing and its-free end 32 supporting an electrical contact 22 and a mechanical contact Il.. lThe electrical contact 33 is adapted to engage s, cooperating contact 35 carried on the end of a longitudinally adjustable contact screw 36, which in turn is supported on a plug, the electrically insulating material rigidly anlxed bymachine screws to an arm of the" support 22.

A second longitudinally adjustable screw'31 has its end adapted for engagement by the free end 32 of the tongue 3| upon movement of the tongue in such away as to break theelectrical contacts 35-23, The mechanical contact u is adapted for engagement by a cooperating mechanical contact 38, carried on the free end of the thermally warpable bi-metallic strip 25, upon a predetermined warp of the strip 25, effected by a predetermined heating thereof. i"

Referring particularly to Figs. 5 and 6, I illustrate therein a spool 4B of copper orllkemetallic heating winding 39 disposed between iiange headsf of the spool, the winding being of nichrome or other heat resistant electrical resistance wire, and o1' a number of suitable relatively electrically insulated convolutions. The riveting projection 88 is projected through a border oi the strip 25' and is then headed over by rivets to make a secure mechanical connection between the kspool lll and strip 2E for the eiilcient conduction of heat therebetween. A

As'illustrated at 4f, I may make this spool of various sizes, so as to operate with various de- Brees of emciency to store heat communicated to it by the winding 38, the spool I0 and the stnp 25 operating for a purpose later to be made clear,

as a reservoir. and radiator o! 'heat communl.

cated thereto by the winding.

In the operation of the mechanism later described, it is important that heat generated in the winding, shall be stored accumulatively to an appreclable extent, and my invention contemplates the storage of heat in the bi-metallic element comprising the strip 25 and spool 40, so that when electrical current ilow through the winding 29 is interrupted for a period of seconds, that an undue cooling of the strip 25 in portions adjacent the projection 39, shall not be accomplished beyond a predetermined rate, even upon conditions of low atmospheric temperatures.

The thermally warpable strip 25 may comprise various materials, such as two superposed sheets of different steel and nickel-steel alloys, or superposed strips of steel and brass, and the like, and

may be of various dimensions and may take various -forms.

Thermally warpable bl-metallic sheets of metal are todaycommercially manufactured in widely varying thickness and can be cut to any desired lengths and widths. Commonlysuch strips are made oi'a relatively small thickness` of "Invar" steel and a greater-'thickness of brass or the like. The two sheet strips are welded, brazed, or otherwise intimately secured together by their contignous surfaces and are capable o! being cutand formed as a single sheet of metal'.

In the type of strip which I preferably employ and which is best illustrated in Figs. l, 2, 4, '1 and 8, and which may be advantageously employed alike for controller and indicator oi' my improved gauge, the heating element 8| for the indicator and 82 for the controller, is in each case, mounted on and adapted to heat only one of. a pair of longitudinally joined, opposltely disposed warpable strip elements, andvwhich are preferably practically thermally lnsulated from each other. 'I his arrangement is for the purpose o! insuring that only one o! the strips will be eilectively electrically heated, whereas both will be exposed to the same prevailing temperatures of the surrounding air.

Fig. f1 shows the composite thermostatlc strip havingy longitudinally aligned thermostatlcally warpable strip elements 1| and 12 rigidly joined together by a relatively heat insulating joint 12, held in place by rivets 1I.

The strip 12 is 4inverted relative to so that upon increased atmospheric temperatures, to which the two strip elements are alike exposed, `it will warp its free end 1l upwardly, as illustrated, while the free end oi the strip 1I, which carries the strip 12, will be moved downwardly.

The dimensions of the two opposltely warpable elements 1| and 12 are so chosen that when the composite strip is exposed to changes o! atmospheric temperature, the two strip elements will warp opposltely to eiIect opposite moving etiects "on the contact carrying end v15 oi the strip 12, and

therefore the lever, engageable by the contact of the lstrip 12, will not be actuated upon mere changes of atmospheric temperature, to which the controller, such as shown at the bottom oi Fig. 8, may Ybe exposed.

Fig. 8 illustrates also the use of such a coniposite strip, as illustrated in Fig. 7, to operate an the strip 1| I.

fill

at 1I, and engaged at a bifurcated end 19 of the free end l0 oi the composite strip having longitudinally aligned joined strip elements 12' and 1|', the element 1i of which, only,'carries an 'electrical heating element 52, rigidly riveted to it. as best illustrated in Fig. 7, andafter the manner illustrated in Fig. 6, except that in Flg.'8. the heating element 8l also is employed as a nxed support for the strip 1I. v

Such an arrangement is desirable to be employed wherever the controller and indicator of my improved indicating system, are so disposed that they will be exposed to diilerent atmospheric temperatures.

Such a condition might prevail, for instance, where the controller is carried by the gasoline tank on the outside of a closed vehicle, whereas the indicator is carried on the inside of the vehicle, which is provided with means for heating the interior of the vehicle. On a coldl wintry day it will be readily appreciated that there might sometimes be a did'erence of 50 Fahrenheit, or more. between theexterior and interior oi' the vehicle. y

In Figs. 3 and 4 the above described thermally compensated strip is shown, with the associated heating element now to be described.

Either the supported orthe supporting strip may be electrically heated to accomplish the purposes set forth therein of securing a composite strip operatively insensible to changes ol atl'nospheric temperature. but adapted to move` a portion of its length to effect the useful controliink and indicating functions as described.

For instance, in the embodiment of my invention illustrated in Figs. 3, 4. 7 and 8, the supporting strip 1l is electrically heated in addition to being exposed to atmospheric temperatures, whereas the supported strip comprising the free end of the strip. shown at 12. is exposed but to little of the electrically derived heat, but is, of'

course, exposed to atmospheric` temperatures.l In such cases. the free end of the strip merely acts as an arm to communicate wlmi!!! movements electrically effected by the Vsupported vend of the strip and to 'compensate such movements for variations in atmospheric temperatures.-`

However, the alternative arrangementwmay be employed as illustrated in Figs. 1 and v'a'..v'vherein the heating winding 30", and Il", respectively, is applied to the supported strip portion carrying the actuating mechanical contactsy" and Il' respectively.

In such a case, the compensating portion .l and respectively, for each strip surface to shift the support for. the electrically free endo! the strip, according tov the prevailing 'atmospheric temperatures to compensate therefor.

Figs. l and 21illustrate also an alternative method of applying the heating to the strip, wherein the metallic spools such as'I shown at 4t, Pig. 5, are dispensed with winding' applied preferably in a single layer vto the bi-metallic strip. Either' plan maybe followed, aithough generally I prefer the vuse of the metallic heat storing spools 4l, of predetermined mas.

Interposed between the tnnguell and the reenforcing disks I1 of the I provide a link to communicate motion from the diaphragm to the tongue. said link comprising abilurcated holder 4| and pointed pin l2 swivelably supported by its non-pointed end between the `forks of the support 4l, which is rigidly secured to the disk i1. The tongue Il is suitably recessed on-its surface r`axially in line with the center of the diaphragm, the recess being preferably conical in form and having side walls ilaring outwardly to -swiveiing axis so that slight 4I,- with associated apparatus a greater extent 'than the walls of the pointed end of the pin 42,'so that the point of the pin 'may make a universal Joint connection with the bottom end of the recess. j

The recess 43 is disposed intermediate the free end of the tongue 3| and its swiveling axis, which includes the pivot screws 29 and the turned-up ears 44 of the integrally joined amature It and tongue Il. At the same time, however, the recess 43 is disposed very closely adjacent to such movements of the lthis multiplying by a-relatively slight pres' A lever relationship also exists between the effcctive force exerted upon the amature Il, electromagnetically effected by the pole of the electromagnet core 4l, relative to the forces exerted upon the free end of the lever, as above noted, and ffl-r the purpose later made clear in the descripy tion ofthe operation ofthe device.

Referring more particularly to Fig. l. I showtherein a source of electrical current 4t, an autofmotive vehicle ignition circuit switch 41, an indicator 2, shown more in detail in Fig. 8 and a primary 'ignition circuit conductor. 4l, current through which is controlled by the operation of the switch 41, together with a circuit conductor 4l. which is joined to the ignition circuit conductor 4l and extends therefrom through the apparatus diagrammatically illustrated in Fig. 1, but more completely illustrated in Fig. 3. Ihis apparatus comprises the'multipiy connected e and heatingenergiaing windings for the magnet 21 .and 'thermally warpable strip 2l, respectively,

and the circuit thereof'is continued through the controlling electrical contacts 33 and the latter supported by the adjustable screw Il, and lever tongue end Il, which is electrlcallyconnected to the frame of the automotive vehicle indicated diagrammatically at Il, Joined to the opposite .terminal of the source-of current 4l. This betheusualstoragebatterynow commonlyiued by automotive vehicles. l

Interposed in -the'circuit conductor 4I and intermediatet'he switch 41 and the apparatus of Fig'. 3. is the electrical indicator 2 such as that as shown in l'glg. 8 which comprises a beating winding l2, lini/association with means for indicating the temperatures effected by' intermittent flow of electrical current in the winding l2. Such in- "dicatlng means are herein illustrated as a compostte strip` being a heat compensated strip having sections1l' and 12', the section 1|.substantially above being heated bycurrent through/the winding I2, as before described. y

v 'Ihe operation of the system of my invention will now be describcd.- it being understood liquid fuel, such as gasoline is supplied through a fillingopening li of the tank I, a's indicated at N, and to I level L, Fig. l, this level being attained gradually within the tube 1 by communication of'the liquid -fuel from the tank 'i to the interior of the tube. throug hthe thelateralwallofthetube,atthebottomofthe tank, and the nlling 0f thekptcealfllntelmediate the partition discs I and i2 at the -bottom of the tube, and the spaces 58 disposed intermediate the discs I2 and the diaphragm I5, flow between the different compartments being effected through the orifices B, and I4, as

i previously related.

The diaphragm I5 will tend to be pressed downwardly by the Weight of the fluid disposed above and with a force depending on its area, and which pressure will be effectual to tend to move. the central portion of the diaphragm with a force proportional to the weight of the column of liquid supported by the diaphragm.

The central portion of the diaphragm will communicate such pressure by the pin 42 to the recessed point 43 on the lever 3|, which is adapted to swivel about an axis 28. The free end of the lever tongue 3| will therefore be deflected downwardly against the contact 35 to close the energizing electrical circuit for the electromagnet 21 and the heating winding 39 for the thermally warpable strip 25, and which circuit was previously described. Also the heating winding 52 on the indicator 2 will conduct current flow to heat the bulb simultaneously with the periods of heating of the strip 25 by its winding 39.

As illustrated in Fig. 5, the heating of the strip 25 is capable of being effected by first heating a mass of metal contained in the metallic spool 40, and this is accomplished at a rate depending upon the amount of mass in the spool, the thermal properties of the metal, its exposed radiating surface, and the properties of metal in, and the radiating surface of, the contiguous portions of the strip 25. The similar spool 52 of the indicator actuating strip and its winding are preferably proportioned to heat and cool at the same or at somewhat less than the same rate as the heating and cooling of the warpable strip 25 is accomplished.

The spools 40 and 52 are preferably made of copper or brass and comprise a considerable amount of the metal so that heating of the entire mass will proceed accumulatively while current by increments of heat, is supplied by intermittent current impulses through the electrical resistance units 39 and 52, respectively, to heat them. The intermittent communication of heat increments to the spools 40 and 52 is communicated more continuously therefrom to their respective sections which will be continuously warped to a degree commensurabie with the temperature of the spool 40, which by the mass of metal, retains heat stored therein between current impulses.

No necessity for compensation for differences of voltage of the source 46 need be provided and the system is adaptable for use over the entire range of atmospheric temperatures which may be experienced under conditions of low atmospheric temperatures, the heating elements 40 and 52 will automatically be continued to be energized for longer intervals than where the atmospheric temperatures are higher, but with the same ultimate effect.

Coincidental with the heating of the strip 25 and the thermometer bulb 54, the electromagnet 21 will be energized and will suddenly supplement the force exerted by the liquid supporting diaphragm I5 on the tongue 3|, to press the elec--` trical contacts 33 and 35 somewhat more tightly together to insure that a good contact is made, and to further provide for a subsequent snapaction breaking of these contacts. I contemplate herein other equivalent instrumentalities for achieving such snap-action".

After an initial heating of electrically heated and of the warpable strip 25 has progressed long enough to cause the mechanical contact 38, carried by the end of the warpable strip, to engage the mechanical contact 34, further warping of the strip will communicate pressure to the tongue 3|, accumulatively, for a short interval thereafter, the end of the strip 25 being temporarily restrained from movement responsive to pressure exerted by the bl-metallic strip, because of the pressure of the diaphragm exerted upon it, supplemented by the electromagnetic pull on the armature 30.

However, in a short period of time the warpable strip, restrained from taking its fully developed warped form by the resistance offered by the tongue as aforesaid, and resiiiently deflected from such form by the opposing pressure developed by warping resisted by the magnet and diaphragm, will overcome the counter-pressure of magnet and diaphragm and move the tongue to break the contacts 33-35, which will suddenly eect deenergization of the magnet by breaking of the circuit of the magnet winding.

The sudden relief of the counter-pressure exerted by the magnet, will permit the strip to resiliently snap the tongue upwardly against the pressure of the diaphragm by the stored force resulting from its inherent resiliency, and the mechanical deflection from its fully warped form caused by the force exerted upon the tongue of the magnet.

Thus a snap break of the contacts is had with consequent reduction of arcing at the contacts.

Although my apparatus may be embodied in varying structures for different purposes, I find that for the usual gasoline tank, I may operate the machanism of the embodiment described, with a current strength not exceeding .5 of an ampere, and much lower current strengths may be employed successfully in connection therewith.

Upon breaking of the contacts 33--35, the current flowing through the heating elements 40 and 52, on the controller bimetallic strip and indicator strip, respectively, will be discontinued, and the strip and bulb will coincidentally progressively cool to a point where, due to weight of liquid 56 in the tank, the weight supported by the diaphragm will again overpower the supporting effort of the somewhat cooler strip 25, to close the contacts 33-35, whereupon the cycle just described will be repeated, comprising energization of the magnet 21 to more firmly close the contacts,

an increase of heating of the strip 25, and of the heating periods are of short duration, so short that the indicator hand does not waver to an objectionable amount, the variation being within the limits of error assigned to instruments of .this kind and preferably scarcely noticeable.

Where extreme steadiness of indication is desired, this may be accomplished by increasing the heat storage capacity of the heated indicator element 52. This may be done in various ways,

lthellidioato'r edplrtsisthatwhich `the displacementv element.

increasingthemamcfthespoolthereof; orenclosingthe withacoverofthermalinsus lation, or both.

The heat storage capacity of the indicator heatl will permit the bulb tc accumulate heat at a rate that will enable it to indicate the amount of i, nearly as rapidly as gasoline supply station?, period of at least a minute and the responsiveness of the indicator v,to heating current is proportioned accordingly; subsequent periods of heating are individually-much shorter. v

Referring now to .the embodiment of my invention illustrated in Fig. 2, the apparatus is similarly organized, except that therein, the diaphagm il' is adapted to lbe level of the tank i', and Supports a displacement ther tankn aired at the element il secured to its lower surface, and

which may preferably be a wood rod' carrying a predeterminedfnumber of weights, such as leadP shot I2, in a bottom recess. displacement element Il made such, relative to its displacement volume, that when the tank is f ull of liquid fuel, the rod li will stilh exert a slight predetermined downward pull on the center of the diaphragm I5', on account of its aggregate weight, exceeding its buoyancy.

The weighting of the is thereby preferably In operation, the electricallyvheated end of the strip 25,', by warping periodicallyrovercomes the force eifected by weight of the displacement element plus a slight pull effected byl the magnet.

gasoline in unfilled tank AThis usually takes a,

placed above the,

the length of the heating periods. relatively to the cooling periods depending upon the amount ofthe weight, whihin turn is determined by the relative part of its length not atthe time immersed in the liquid fuel Il'. .A tube 1', closed at its bottom end, except for minute lateral apertures l', near its bottom, surrounds the displace-- ment element, protects'it, and during lagitation of the tank by movement of the vehicle, prevents rapid changes of level in'iluencing the weight'of this embodiment of my will came the displacement element to be vof slight eifective weight, and therefore'A little heating of the ble strip 2l' will be required to effect intermi nt operation of the contacts, and, therefore, the band of the' yindicator 2' will indicatepby a slight movement from normal position, 'a relatively large amount of gasoline; whenthe tank is empty pr nearly empty, more heat will be to effect warping of the strip 28 sumcientlv to overcome the full weight of the displacement velement Il, and so the controlling contacts will be maintainedclosed for longer periods relative lto their periods of opening. and consequently the indicator heatingelem'entwillbeheatedforlongerperiods and will retain more accumulated heat to cause band to be moved toa position much more remote from im normal pasition.`

'Iherefora an indication responsive to a relatively Bretter heating of the indicategreaterdepletionofthefuelmpply. The indicationsintheindicator forthe controllingL apparatus of l'iga. 3 and 4.

f that illustrated in'l'ig. 2, dne the embodiindvicator Strip will- -element It. The free y carries,.by a preferably flexible expansion I an electrical contact Il when the yfree .ends ofthe 40 being thesameasillustratedinll'ig.l,and

creased electrical heating 'tration of twodifferent 'level indicating systems whichiioatsarebuoyantandoperatein n objectionable manners onlccoimtof theirbutry-l ancy. l" y f In the embodiment of my invention illustrad, although the drawings, I preferably proportion the parts ofthe indicator and'theparts of the switch operating for heat storage capacityand for dissipation of heat, so that both' lelectrically heatedunits at the controllerand at the indicator will cool in unison and at the same rates.

\In this'way I prevent overthrow of the indi-'- cator needle when the manually operated switch 4l, Fig. 1, is ir'st closed. and avoid gradual` changes of vreading by indicator` as is otherwise apt/.to where these proportions are'departedfrom, variously. Ir. this embodiment, the heatingcurves of the thermostats at the controller and at the indicator are Substantially` alike in form.

The' diaphragm is carried on 'ailanged cup I' having an annular exteriorly threaded hollow stem -4 screw threaded into an` interiorly threaded hollow boss I' of the top wall of the tank I. QZ', inter-connects the reenforced central por#` tion o f the diaphragmdwith thejever tongue 3i', swivelable about an axis 29'. The lever comprises a lever arm Il forming an armature for an electromagnet 2l', a second carrying at its free yends a mechanical contact engageable with a on the free ends o'f the bi-metallic strip 2l' edly mounted on the compensating strip Il at 2Q'.

The stripI is adapted l wardly when `heated by the supported heating ends of the .tongue also y n.- engageable with an adinstable contact 35', tongue 'Il' is moved downwardly by theloverpowering eii'ect of the weight ofthe displacement element 'Il'. the electromagnetic pull of the magnet 21 on the armatureA 3l', or both.

-The operation of the device will be stood. the circuit connections preferably' l interconnecting the con-` a circuit conductor Il' element treuer sttne tank with the 1 of the indicator 2', which though not bc constructed inatbe marmer -of that shown in Fig. 8, as described, the strip being, however, preferably reversed and' the hand therefore made movable 'from right to left, prefaably upon in- The above embodimentsare chosen for illus- Wlys" of Operating uid v in accordance, broadly, withtheprinciplesofmyinventiomandlam aware that numerous and herein mus*- arm, a thermostat adapted to exert thermallyv elected force on the switch arm in pening direction at a point remote l pivot, asource of current, an electrical'heating similar contactll carried.

not yrelatively to scale, 4

neatand 1o a creeping action at the A link, such as a piece of veryne wire arm or tongue Il', 30

towarpitsfreeendup-M nowunder- 4s shown may of the beating elementi l extensivedepartmes ,may be had from the embodiments trated and described but withoutdeparting from tbespirit of my'invention.

I claim:-

controller fordtranamltting 05 adiacent tbeaxis ci oscillationelementforheatingsaidtner. 1I

mostat; electrical circuit conductors interconnecting said switch contacts and said source 4of current withlsaid heating element, whereby said switch under the joint control of said pressure producing means andsaid thermostat is operated periodically to close responsive to pressure and open responsive to heating of the thermostat to periodically electrically energize said heating element, and an electro-magnet energizable by current from said source through the switch contacts when closed and disposed to exert a yieldable force on the switch arm at a point adjacent 'the pivot of oscillation and in the direction Vto assist the pressure producing means to yieldingly hold the switch closed and adapted to eiect a snap-action release of lthe switch arm when opened by the thermostat. y

2. In an electrical impulse transmitting system, a switch comprising an oscillatable arm and contacts, a variable pressure means for applying switch closing pressure, an electromagnet cooperating with said variable pressure means to maintain the contacts closed when energized, a thermostat adapted to exert thermally effected switch opening force when the contacts are closed, an electrical heating element for heating said ther-P mostat, electrical circuit connectors interconnecting a current source, said switch contacts, said electromagnet, and said heating element, whereby said switch contacts are closed responsive only to the variable pressure means, are conjointly maintained closed by the said pressure means and the electromagnet, and are opened responsive only to the force of said thermostat, the'electromagnetic restraining force being nulliiied abruptly upon opening of the contacts to eiect a `snapaction movement therebetween.

3. In an electrical controller for transmitting impulses in accordance with a variable pressure, y a switch comprising contacts and an oscillatably acca-roo mounted switch arm, variable pressure producing means for applying switch closing pressure yieldably to the switch arm, a thermostat adapted to exert thermally effected force on the switch arm in the switch-opening direction, a source of current, an electrical heating element for said thermostat, electrical circuit conductors interconnecting said switch contacts and said source oi current with said heating element, whereby said switch under the joint control of said pressure producing means and of said thermostat is operated periodically to close responsive to pressure and open responsive to heating of the thermostat to periodically electrically energize said heating element,

` and an electromagnet energizable by current from said source through the switchl contacts when closed and disposed to exert a yieldable force on the switch arm in the direction to assist the pressure producing means to yieldingly hold the switch closed and adapted to effect a snap-action release of the switch arm when opened by the thermostat.

4. An electric controller as described in claim l and in which'the switch comprises a stationary contact and a contact on the switch arm and the stationary contact acts as a stop to limit switch arm oscillatory movement in the contact-closing direction and a second stop is vprovided to limit magnet-effect snap-actionmovement in the other directiom 5. An electrical indicating system as described inY claim 1 and wherein heat storage means is movingly associated with the thermostat and in thermal contact therewith whereby undue cooling oi.' the thermostat will not be effected by ambient, temperature upon opening of the switch contacts and switch opening action will be delayed to eiect a snap-action release oi the switch arm.

FRANK M. SLOUGH. 

